Back to EveryPatent.com
United States Patent |
6,089,316
|
Spray
|
July 18, 2000
|
Wire-wrapped well screen
Abstract
A well screen for placement within wells used to filter out impurities from
the fluid entering the well. In the preferred embodiment, the well screen
comprises a spirally-wound wire forming a cylinder with gaps between the
layers of wire. The layers of wire are attached by spacers placed within
the gaps and on the surfaces of the wire such that the spacers do not
extend radially beyond the inner and outer edges of the wire. The outer
edge of the spacer can be flush or slightly recessed from the outer edge
of the wire to create greater open area for which fluid can flow through.
The inner edge of the spacer can also be flush or slightly recessed from
the outer edge of the wire. In the alternate embodiment, the well screen
comprises a plurality of rings stacked atop each other and connected
together by spacers located at intervals around the circumference of the
rings. The spacers are attached to the wire or rings by a secure means
such as welding which results in a single unitized screen that is
structurally rigid. The spacer/ring configuration allows greater open area
on the screen which increases fluid flow and efficiency through the
screen.
Inventors:
|
Spray; Jeffery A. (714 W. Keystone Ave., Woodland, CA 95695)
|
Appl. No.:
|
123197 |
Filed:
|
July 27, 1998 |
Current U.S. Class: |
166/227; 166/232 |
Intern'l Class: |
E21B 043/08 |
Field of Search: |
166/227,228,231,232
|
References Cited
U.S. Patent Documents
880635 | Mar., 1908 | Decker | 166/232.
|
1273236 | Jul., 1918 | Layne | 166/232.
|
3584685 | Jun., 1971 | Boyd.
| |
3712373 | Jan., 1973 | Bearden et al.
| |
4299283 | Nov., 1981 | Gryskiewicz.
| |
4381820 | May., 1983 | Wagner.
| |
5095990 | Mar., 1992 | Best et al. | 166/227.
|
5355949 | Oct., 1994 | Sparlin et al.
| |
5785122 | Jul., 1998 | Spray | 166/227.
|
Foreign Patent Documents |
0 617 195 | Sep., 1994 | EP.
| |
3913986 | Mar., 1989 | DE.
| |
496877 | Sep., 1970 | CH.
| |
1 400 673 | Jul., 1975 | GB.
| |
Primary Examiner: Neuder; William
Attorney, Agent or Firm: O'Banion; John P.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of copending application Ser.
No. 08/904,883 filed on Aug. 1, 1997, now U.S. Pat. No. 5,785,122.
Claims
What is claimed is:
1. A well screen, comprising:
(a) a wire wound spirally to form a porous cylinder having a plurality of
spaced-apart windings, said cylinder including an outer surface and an
inner surface;
(b) a plurality of individual spacers positioned within gaps between said
windings and further positioned between said outer surface and said inner
surface of said cylinder, said spacers including an inner edge and an
outer edge, said inner edge and said outer edge defining a longitudinal
axis therebetween of said spacers; and
(c) means for securely attaching said spacers to said windings.
2. An apparatus as recited in claim 1, wherein said inner edge of said
spacer is flush with said inner surface of said cylinder, said outer edge
of said spacer flush with said outer surface of said cylinder.
3. An apparatus as recited in claim 1, wherein said inner edge of said
spacer is recessed from said inner surface of said cylinder, said outer
edge of said spacer is flush with said outer surface of said cylinder.
4. An apparatus as recited in claim 1, wherein said inner edge of said
spacer is recessed from said inner surface of said cylinder, said outer
edge of said spacer is recessed from said outer surface of said cylinder.
5. An apparatus as recited in claim 1, wherein said longitudinal axis being
generally perpendicular to a tangent of said windings between which said
respective spacer is positioned.
6. An apparatus as recited in claim 1, wherein said spacers are positioned
such that said longitudinal axis forms an acute angle from a perpendicular
to a tangent to said windings between which said respective spacer is
positioned.
7. An apparatus as recited in claim 1, wherein said spacers each having a
width and a thickness, said width of each said spacer increasing as said
spacer extends toward said inner surface of said cylinder, said thickness
of said spacer increasing as said spacer extends toward said inner surface
of said cylinder.
8. An apparatus as recited in claim 1, wherein each said spacer has an
elliptical shape with an acute end and an obtuse end, said acute end of
each said spacer oriented towards said outer surface of said cylinder.
9. An apparatus as recited in claim 1, wherein each said spacer is
parallelogram-shaped with four curved corners.
10. An apparatus as recited in claim 1, wherein said wire has a trapezoidal
cross-section having an apex oriented towards said inner surface of said
cylinder.
11. An apparatus as recited in claim 1, wherein each said spacers are
attached between said windings at intervals such that a portion of said
gaps lie directly above and directly below each said spacer.
12. An apparatus as recited in claim 1, wherein each said spacers are
shaped such that fluid passing through said gaps create a vortex.
13. A well screen, comprising:
(a) a wire wound spirally to form a porous cylinder having a plurality of
spaced-apart windings, said cylinder including an outer surface and an
inner surface; and
(b) a plurality of individual spacers welded between said windings, said
spacers including an inner edge and an outer edge, said inner edge and
said outer edge defining a longitudinal axis therebetween of said spacers;
(c) wherein each said spacers are attached between said windings at
intervals such that a portion of said gaps lie directly above and directly
below each said spacer.
14. An apparatus as recited in claim 13, wherein said inner edge of said
spacer is flush with said inner surface of said cylinder, said outer edge
of said spacer flush with said outer surface of said cylinder.
15. An apparatus as recited in claim 13, wherein said inner edge of said
spacer is recessed from said inner surface of said cylinder, said outer
edge of said spacer is flush with said outer surface of said cylinder.
16. An apparatus as recited in claim 13, wherein said inner edge of said
spacer is recessed from said inner surface of said cylinder, said outer
edge of said spacer is recessed from said outer surface of said cylinder.
17. An apparatus as recited in claim 13, wherein said longitudinal axis
being generally perpendicular to a tangent of said windings between which
said respective spacer is positioned.
18. An apparatus as recited in claim 13, wherein said spacers are
positioned such that said longitudinal axis forms an acute angle from a
perpendicular to a tangent to said windings between which said respective
spacer is positioned.
19. An apparatus as recited in claim 13, wherein said spacers each having a
width and a thickness, said width of each said spacer increasing as said
spacer extends toward said inner surface of said cylinder, said thickness
of said spacer increasing as said spacer extends toward said inner surface
of said cylinder.
20. An apparatus as recited in claim 13, wherein each said spacer has an
elliptical shape with an acute end and an obtuse end, said acute end of
each said spacer oriented towards said outer surface of said cylinder.
21. An apparatus as recited in claim 13, wherein each said spacer is
parallelogram-shaped with four curved corners.
22. An apparatus as recited in claim 13, wherein said wire has a
trapezoidal cross-section having an apex oriented towards said inner
surface of said cylinder.
23. An apparatus as recited in claim 13, wherein each said spacers are
shaped such that fluid passing through said gaps create a vortex.
24. An apparatus as recited in claim 13, wherein each said spacers are
attached between said windings at intervals such that a portion of said
gaps lie directly above and directly below each said spacer.
25. A well screen, comprising:
(a) a plurality of concentric spaced-apart rings forming a porous cylinder,
said cylinder including an outer surface and an inner surface;
(b) a plurality of individual spacers positioned in gaps between said
rings, said spacers including an inner edge and an outer edge, said inner
edge and said outer edge defining a longitudinal axis therebetween of said
spacers; and
(c) means for securely attaching said spacers to said rings.
26. An apparatus as recited in claim 25, wherein said inner edge of said
spacer is flush with said inner surface of said cylinder, said outer edge
of said spacer flush with said outer surface of said cylinder.
27. An apparatus as recited in claim 25, wherein said inner edge of said
spacer is recessed from said inner surface of said cylinder, said outer
edge of said spacer is flush with said outer surface of said cylinder.
28. An apparatus as recited in claim 25, wherein said inner edge of said
spacer is recessed from said inner surface of said cylinder, said outer
edge of said spacer is recessed from said outer surface of said cylinder.
29. An apparatus as recited in claim 25, wherein said longitudinal axis
being generally perpendicular to a tangent of said rings between which
said respective spacer is positioned.
30. An apparatus as recited in claim 25, wherein said spacers are
positioned such that said longitudinal axis forms an acute angle from a
perpendicular to a tangent to said rings between which said respective
spacer is positioned.
31. An apparatus as recited in claim 25, wherein said spacers each having a
width and a thickness, said width of each said spacer increasing as said
spacer extends toward said inner surface of said cylinder, said thickness
of said spacer increasing as said spacer extends toward said inner surface
of said cylinder.
32. An apparatus as recited in claim 25, wherein each said spacer has an
elliptical shape with an acute end and an obtuse end, said acute end of
each said spacer oriented towards said outer surface of said cylinder.
33. An apparatus as recited in claim 25, wherein each said spacer is
parallelogram-shaped with four curved corners.
34. An apparatus as recited in claim 25, wherein said wire has a
trapezoidal cross-section having an apex oriented towards said inner
surface of said cylinder.
35. A well screen as recited in claim 25, wherein each said spacers are
shaped such that fluid passing through said gaps create a vortex.
36. An apparatus as recited in claim 25, wherein each said spacers are
attached between said windings at intervals such that a portion of said
gaps lie directly above and directly below each said spacer.
Description
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
REFERENCE TO A MICROFICHE APPENDIX
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains generally to well screens for oil, gas, mineral,
and groundwater production, and groundwater monitoring, and more
particularly to an improved one piece wire-wrapped well screen.
2. Description of the Background Art
When water, oil and gas producing wells are drilled through unconsolidated
formations, the produced fluids generally contain particulate matter,
usually sand. The production of sand, along with the fluids, is an
undesired consequence because the sand causes extra wear and abrasion of
production tubing, valves, pumps, and other equipment used to produce and
remove fluids from the wells. It is therefore beneficial to avoid or
minimize the production of sand or other particulate matter during the
production of fluids from wells.
One method of accomplishing the reduction of sand or particulate production
is by "gravel packing" the well during completion operations. Such gravel
packing includes providing on the production conduit or tubular work
string a slotted or ported cylindrically shaped member, generally known as
well screens, which restricts the passage of particles into the interior
of the conduit. For many years, well screens have been used in wells to
permit fluid to flow through the screen and into the well while retaining
sand and other particulate matter outside the well screen.
A common well screen design uses longitudinal supports tangentially welded
to a helical band to produce a frame upon which strainer elements or
inserts are attached. The strainer elements or inserts fill the gaps
between the longitudinal and helical bars and serve to retain sand and
other particulate matter. In such designs, the filtration screen is not
self-supporting and is dependent on the frame for rigidity.
Other designs of well screens incorporate "projections" that are formed in
a stack of rings and which protrude parallel to the longitudinal axis of
the structure and perpendicular to the rings. This enables installers to
adjust the gap between the rings during installation of the well screen.
However, the projections do not provide structural rigidity to the screen
and merely rest on the inner surface of the rings, thereby resulting in an
undulated inner well screen surface.
Current screen design practice assumes a 1% ellipticity, which
significantly reduces collapse strength and requires use of excess
materials in order to achieve the desired resistance. The general tensile
calculation for conventional wire wrap screens includes an approximate 30%
welding de-rating effect due to welding of the wire or ring apex to the
rod tangent, which is also a corrosion enhancer. Wire/rod screens have no
torsional qualities. Corrosion, well construction defects, or
manufacturing errors occasionally lead to holes or cracks in well casings
or screens. One approach toward repair is to spot a serrated piece of
slightly under-sized casing and hydraulically pressing this piece over the
problem area, essentially forming a patch. This is impractical due to the
presence of vertical rod protrusions in conventional wire wrap screens.
Conventional wire wrap screens normally show mostly steel, not open area
available for fluid to flow through. The usual range of open area
percentage exposed to abutting geological formations is 20%-50% with a
fluid entrance efficiency of approximately 90% at best.
BRIEF SUMMARY OF THE INVENTION
By way of example and not of limitation, the present invention is a well
screen which generally comprises a wire which is spirally wound to form a
cylinder with spaces between each layer of wire. Spacers between the wire
at intervals around the circumference of the well screen serve to attach
the layers of wire together. The spacers do not extend radially beyond the
inner or outer edge of the wire. The spacers can be flush with either the
inner and/or outer edge of the wire or recessed from either the inner
and/or outer edge of the wire. The spacers are permanently and securely
attached to the wire by means such as welding, resulting in a single
unitized well screen that is also very structurally rigid.
In an alternate embodiment of the invention, the well screen comprises a
plurality of rings stacked atop one another and connected together by
spacers located at intervals around the circumference of the rings,
generally forming a cylinder. The spacers do not extend radially beyond
either the inner or outer edge of the rings. The spacers can be flush with
either the inner and/or outer edge of the ring or recessed from either the
inner and/or outer edge of the ring. The spacers are attached to the rings
in the same manner as with the spiral wire well screen design.
This spacer/wire and spacer/ring design allows for fabrication and use of
any thickness or width of wire or ring. By increasing wire or ring
thickness and essentially melting the vertically oriented rod components
of wire wrap screen into the thickness of the rings, and then welding
these in place, superior strength is created even with less width profile.
Since it is advantageous to provide more open area through which the fluid
can enter the screen, aperture dimensions can be varied by adjusting ring
thickness, width, spacer dimensions, spacer shapes, placement and
orientation, in order to improve fluid flow therethrough, while
simultaneously increasing strength and rigidity and reducing material
requirements.
The spacer shape is variable, which allows the manipulation of fluid
dynamics. Improved fluid flow characteristics can be achieved, thus
increasing flow efficiency while reducing corrosion and plugging
tendencies of conventional well screen designs.
Since the spacers do not extend beyond the inner surface of the well
screen, the flush inner surface of the well screen also allows ready
installation of "swaged" patches for damage repair and eases repair when
fissures develop during use. The flush inner surface allows the use of
zone isolation devices with greater effectiveness. The flush inner surface
also allows rotation activities within the screen without interference or
catching of rods on the rotating device which would otherwise damage or
destroy the screen.
This design eliminates or minimizes problems associated with tangential
welding and normal stress points as such welds are more robust and less
susceptible to corrosion. In addition, any length of well screen can be
easily manufactured because no rods are used.
An object of the invention is to provide a one-piece rigid well screen
which is selfsupporting, has increased structural strength and which can
be manufactured efficiently and reliably.
Another object of this invention is to provide a greater area through which
fluid can flow, thus enhancing the fluid entrance capability and
efficiency.
Yet another object of the invention is to provide for a flush inner and
outer surface. The flush inner surface allows the well screen to be
cleaned using techniques such as vertical wire brushing and rotary
scratching.
Further objects and advantages of the invention will be brought out in the
following portions of the specification, wherein the detailed description
is for the purpose of fully disclosing preferred embodiments of the
invention without placing limitations thereon.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be more fully understood by reference to the following
drawings which are for illustrative purposes only:
FIG. 1 is a fragmentary side elevational view of a spiral wire well screen
in accordance with the present invention.
FIG. 2 is a top view of the well screen showing the spacers angled.
FIG. 3 is top plan view of the preferred embodiment of a ring spacer in
accordance with the present invention shown in relation to a fragment of a
wire.
FIG. 4 is top plan view of a second embodiment of a ring spacer in
accordance with the present invention shown in relation to a fragment of a
wire.
FIG. 5 is top plan view of a third embodiment of a ring spacer in
accordance with the present invention shown in relation to a fragment of a
wire.
FIG. 6 is top plan view of a fourth embodiment of a ring spacer in
accordance with the present invention shown in relation to a fragment of a
wire.
FIG. 7 is a cross-sectional view of the well screen shown in FIG. 2 taken
through line 7--7.
FIG. 8 is a fragmentary side elevation view of the well screen shown in
FIG. 2 showing a spacer between two wires and fillet welds between the
spacer and wires.
FIG. 9 is a fragmentary cross-sectional view in perspective of the well
screen shown in FIG. 2 taken through line 9--9.
FIG. 10 is a perspective view of an elliptical spacer in accordance with
the present invention.
FIG. 11 is a perspective view of a parallelogram-shaped spacer in
accordance with the present invention.
FIG. 12 is a side elevational view of a multiple ring well screen
configuration in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring more specifically to the drawings, for illustrative purposes the
present invention is embodied in the apparatus generally shown in FIG. 1
through FIG. 12. It will be appreciated that the apparatus may vary as to
configuration and as to details of the parts without departing from the
basic concepts as disclosed herein.
Referring first to FIG. 1 and FIG. 2, it will be seen that a well screen 10
in accordance with the present invention generally comprises a wire 12
spirally wound to form a porous cylinder. Wire 12 is wound with evenly
spaced gaps 14 between the surfaces 18 of wire 12, with surfaces 18 of
wire 12 attached by spacers 16 between the surfaces 18. Spacers 16 are
positioned at intervals around the circumference of well screen 10 and do
not extend radially from the inner edge 20 or the outer edge 22 of wire
12. An inner surface 24 and an outer surface 26 of well screen 10 is
thereby formed. The "C" in FIG. 1 represents the central axis of well
screen 10.
Referring also to FIG. 3 through FIG. 7, spacers 16 are designed to
minimize disruption of fluid flow along the horizontal axis by using a
streamlined or elliptical design 50. The acute 52 or sharper end of spacer
16 is oriented towards outer edge 22 of wire 12, thus minimizing the
surface area which restricts fluid flow at or near the entry point. As
spacer 16 approaches inner edge 20 of wire 12, spacer's 16 width and
thickness (volume) increases at a slightly slower rate than the greater
volume of the widening gap 14 between surfaces 18 of wire 12. Thus, a
greater net volume of the overall entrance chamber is created, thereby
slowing fluid flow and causing less turbulence against entry.
Preferably, the outer or acute end 52 of spacer 16 does not extend to outer
edge 22 of the wire 12, thus forming a recess 28 from outer surface 26 of
well screen 10, as shown in FIG. 3. This creates a greater open area and
continuous opening through which fluid can flow through, thus enhancing
fluid flow and efficiency. Recess 28 also aids in controlling corrosion as
it reduces the fluid flow rate at that location which consequently reduces
the occurrence of corrosion.
Alternatively, acute end 52 of spacer 16 extends to outer edge 22 of wire
12, as shown in FIG. 4, giving well screen 10 extra strength and rigidity
but reducing the amount of open area. However, the open area given up as a
result of spacer 16 extending to outer edge 22 of wire 12 can be made up
elsewhere, i.e. wider gaps 14 or fewer spacers 16. The number of spacers
16 between each layer of wire 12 varies according to structural, chemical,
hydraulic and economic objectives.
Another variation for spacer 16 includes acute end 52 of spacer 16
extending to outer edge 22 of wire 12 and inner end 64 of spacer 16
recessed from inner edge 20 of wire 12 forming inner recess 66, as shown
in FIG. 5. Yet another variation is to position spacer 16 such that its
longitudinal axis L forms an acute angle .alpha. from a perpendicular P to
a tangent to outer edge 22 of wire 12, as shown in FIG. 6.
Referring also to FIG. 7 and FIG. 9, wire 12 is shown as a cold-rolled
formation of a "Vee-shape" or trapezoidal-shape cross section 30 with the
apex 32 of the "Vee" or trapezoid oriented towards inner surface 24 of
well screen 10. Reducing the width profile (thickness) of the outer edge
22 of wire 12 results in a proportional increase in gap 14, which make up
the fluid producing open areas. Because the apex 32 of wire 12 is oriented
towards the inner surface 24 of the well screen 10, the volume of gap 14
between the layers of wire 12 increases towards the inner surface 24 of
the well screen 10. Ideally, the wire width to gap ratio is in the order
of 1:2, with the gap 14 width (thickness) generally being twice the wire
12 width profile (thickness). To relieve triangular stress, wire 12 is
preferably wound spirally at an angle up to approximately a 6.degree.
inclination as measured from the horizontal plane. It is also contemplated
that wire 12 can have other cross-sectional shapes.
The width of gap 14 between the surface 18 of wire 12 is variable depending
upon the application of the well screen 10. The width is usually based on
the relative size of the formation sand to be excluded. Where sands have a
broad size distribution, a gap width of two times as large as the ten
percentile diameter of the formation sand has been successfully used.
Where sands are generally more uniform in size and rounded, a gap width
equal to the ten to fifteen percentile formation sand diameter is used.
Identically fabricated spacers 16 are used during manufacturing which
results in precisely formed apertures 54, thus allowing for accurate
performance calculations and improved sand and particle filtration. Any
length of spacer 16 can be used with any thickness of wire 12 and placed
at any point along the wire surface 18 in any direction, thus allowing for
optimal hydraulic, structural and chemical considerations. The variable
circumferential position and spacer 16 shape can be used to benefit the
hydraulic behavior of fluids while inside the confines of well screen 10,
in the manner the fluids enter from the formation and in the manner which
they are injected into the formation. There is a slight circulation loss
that occurs as high volumes of water travel through the inner surface 24
from the outer surface 26 of well screen 10, however this circulation loss
can be improved by introducing twists or reliefs to the fluid as it enters
well screen 10 to emulate natural whirling drainage patterns. Theoretical
radial flow patterns into wells are generally not possible due to
geological imperfections so, to equalize entry potential, fluid is forced
into more exposure to the more perfect area of artificial gravel pack by
slightly twisting the fluid flow in a manner commensurate with turbine
pumping activity. Also, injection at different rates can be beneficial for
cleaning applications by creating diversion and vortices in the fluid
flow. Since the spacer system comprises only two separate pieces, spacer
16 and wire 12, cleaner cuts on the inner surface 24 and outer surface 26
can be created, if necessary, during well fishing operations.
The spacer system allows for precise connections between surface 18 of wire
12 by drawing them over a round mandrel or by placing them in a socket and
fusion welding them in place. The result is a significantly reduced
tubular ellipticity, an important consideration in conventional screen
design as most failures occur due to collapse from elliptical induced
weaknesses. Fillet welds 58, as shown in FIG. 7 and FIG. 8, around the
joints of spacer 16 to wire 12 can further strengthen well screen 10 by
reducing triangular stresses. For even greater structural rigidity,
spacers 16 can be positioned on the wire surface 18 mid-way above and
below an aperture 54, which is formed by the surface boundaries of wire 12
and spacer 16 combination. This basically forms a diamond pattern which
reduces leveraged stress across the wire. However, to allow for some
flexibility of well screen 10, spacers 16 are positioned at intervals such
that a portion of gaps 14 lie directly above and directly below each
spacer 16. Therefore, the exact positioning of spacer 16 is driven by the
direction and angle well screen 10 must be contorted.
The flush inner surface 24 of the well screen 10 allows greater penetration
of line scratching (vertical wire brushing) and rotary scratching (rotary
brushing). There is a geometric advantage formed during rotary brushing in
that at the point of contact with inner rods, bristles are deflected away
from the last portion of the sweep through the aperture area. An
alternative spacer design in the form of a parallelogram 60 with curved
corners 62, as shown in FIG. 11, allows both the initial sweep to be
completed and subsequent entry and guiding of the same or new bristles
into the next successive aperture, thus achieving a more thorough
cleaning. It is also contemplated that spacers 16 could be of other
shapes, including but not limited to, straight-edged, curved and
curvilinear shapes. Spacer 16 could also be asymmetrically shaped such
that a vortex is generated by the fluid entering well screen 10 to emulate
natural whirling drainage patterns.
The invention can be manufactured using a conventional secondary cold
rolling process, resulting in greater precision of all aspects of the well
screen 10. This process can be followed by a "bead blasting" polishing
process, to reduce microscopic irregularities on the wire surface 18 that
can contribute to the formation of hydraulic eddies, which are detrimental
to smooth and efficient fluid flow. Both processes serve to increase the
strength of the well screen 10.
The ability to manipulate spacer 16 placement, shape, position, and
quantity allows well screen 10 to flex to fit non-linear wells. There also
exists the possibility to couple any length of the well screen assembly
with swiveling couplings, thus allowing a high degree of directional
change without the need for a manufacturing design change.
FIG. 12 illustrates an alternate embodiment of the invention wherein "C"
represents the central axis of the ring well screen 34. Ring well screen
34 comprises a plurality of rings 36 vertically stacked and attached
together by spacers 16 placed at intervals circumferentially on the
surface 38 of rings 36. Rings 36 are formed by using a cold-rolled
formation of a "Vee-shape" or trapezoidal-shape wire 30, as previously
shown in FIG. 5, which has undergone an electro-resistance and pressure
welding process to form a ring 36. Ring 36 has a generally trapezoidal
cross section 30 with the apex 32 oriented towards the inner surface of
well screen 34. All the other aspects of this ring well screen share a
similarity to the wire well screen previously discussed.
Those skilled in the art will appreciate that the invention herein can be
fabricated from stainless steel, low carbon steel, plastic, polymers,
carbon fiber, ceramics and other materials suitable for use in well
environments. It will also be appreciated that the invention can be used
as a drive point, strainer, filter, or other fluid porous media Although
the description above contains many specificities, these should not be
construed as limiting the scope of the invention but as merely providing
illustrations of some of the presently preferred embodiments of this
invention. Thus the scope of this invention should be determined by the
appended claims and their legal equivalents.
Top